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Alain Philippon

Publications and source records attributed to Alain Philippon.

8 recordsLinked to original sources
PubMed2006

[Bacterial zoonoses: emerging concepts].

Bacterial zoonoses are evolving with changes in society, climate and lifestyles. A hierarchy of non food-borne zoonoses was recently proposed in France, and includes characteristics such as severity criteria and bioterrorism potential. The creation of specific networks and reference centers has provided the means to monitor the emergence (or re-emergence) of zoonoses such as brucellosis and Q fever. Molecular tools have facilitated the detection of bacteria that are transmitted by arthropod vectors (ticks, fleas, etc.) and that cause diseases such as Lyme borreliosis, bartonellosis and ehrlichiosis.

Animals↗
PubMed2003

Molecular and biochemical characterization of a novel class A beta-lactamase (HER-1) from Escherichia hermannii.

Escherichia hermannii showed a low level of resistance to amoxicillin and ticarcillin, reversed by clavulanate, and a moderate susceptibility to piperacillin but was susceptible to all cephalosporins. A bla gene was cloned and encoded a typical class A beta-lactamase (HER-1, pI 7.5), which shares 45, 44, 41, and 40% amino acid identity with other beta-lactamases, AER-1 from Aeromonas hydrophila, MAL-1/Cko-1 from Citrobacter koseri, and TEM-1 and LEN-1, respectively. No ampR gene was detected. Only penicillins were efficiently hydrolyzed, and no hydrolysis was observed for cefuroxime and broad-spectrum cephalosporins. Sequencing of the bla gene in 12 other strains showed 98 to 100% identity with bla(HER-1).

Amino Acid Sequence↗
PubMed2002

BUT-1: a new member in the chromosomal inducible class C beta-lactamases family from a clinical isolate of Buttiauxella sp.

An atypical Enterobacteriaceae strain with a beta-lactam susceptibility pattern of inducible cephalosporinase was isolated in Tenon Hospital (Paris, France) from a patient's skull wound infection. Identifications by the API-50CHE biochemical system and 16S rRNA gene sequencing concluded that it was a member of the Buttiauxella genus. The bla gene was cloned and sequenced. The deduced translated product was a 383-amino acid protein (BUT-1) with 75-78% identity with the chromosomal AmpC beta-lactamases of Citrobacter freundii, Enterobacter aerogenes, Enterobacter cloacae and Escherichia coli. The isoelectric point of 9.0 and the kinetic constants of BUT-1 were comparable with results described for other Ambler class C enzymes. bla(BUT-1) and the associated ampR transcriptional regulator gene were divergently transcribed from a common intercistronic region, a genetic organization already described for other inducible class C beta-lactamases. The deduced amino acid sequence of AmpR shared 85% and 81% identity with AmpR from E. cloacae and C. freundii respectively.

Amino Acid Sequence↗
PubMed2002

Chromosomal ampC genes in Enterobacter species other than Enterobacter cloacae, and ancestral association of the ACT-1 plasmid-encoded cephalosporinase to Enterobacter asburiae.

The amplification and sequence of ampC genes in Enterobacter asburiae, Enterobacter cancerogenus, Enterobacter dissolvens, Enterobacter hormaechei and Enterobacter intermedius bring the number of known cephalosporinase sequences from the genus Enterobacter to seven. Expression in Escherichia coli of the ampC genes from E. asburiae, E. hormaechei and E. intermedius established the functional nature of these genes. ampC from E. asburiae shows 96.5% identity to bla(ACT-1) encoding a plasmid-borne cephalosporinase previously believed to derive from Enterobacter cloacae. The reassignment of ACT-1 ancestry to E. asburiae is confirmed by the 95.5% identity between ampR upstream of bla(ACT-1) and ampR from E. asburiae.

Anti-Bacterial Agents↗
PubMed2002

Diversity of CTX-M beta-lactamases and their promoter regions from Enterobacteriaceae isolated in three Parisian hospitals.

Nine clinical isolates of Enterobacteriaceae (six Escherichia coli and three Proteus mirabilis) isolated in three Parisian hospitals between 1989 and 2000 showed a particular extended-spectrum cephalosporin-resistance profile characterized by resistance to cefotaxime and aztreonam but not to ceftazidime. CTX-M-1, CTX-M-2, CTX-M-9, CTX-M-14 and two novel plasmid-mediated CTX-M beta-lactamases (CTX-M-20, and CTX-M-21) were identified by polymerase chain reaction and isoelectric focusing (pI>8) and were associated in eight cases with TEM-1 (pI=5.4) or TEM-2 (pI=5.6) beta-lactamases. We used internal ISEcp1 and IS26 forward primers and the CTX-M consensus reverse primer to characterize the CTX-M beta-lactamase promoter regions and showed their high degree of structure diversity. We found upstream of some bla(CTX-M) genes, a 266-bp sequence 100% identical to the sequence upstream of the Kluyvera ascorbata beta-lactamase gene, suggesting that this chromosomal enzyme is the progenitor of the CTX-M-2/5 cluster.

Base Sequence↗
PubMed2002

Characterization of CMY-type beta-lactamases in clinical strains of Proteus mirabilis and Klebsiella pneumoniae isolated in four hospitals in the Paris area.

We isolated five clinical strains (three Proteus mirabilis and two Klebsiella pneumoniae) with beta-lactam resistance phenotypes consistent with production of an AmpC-type beta-lactamase. The predicted amino acid sequences of the enzymes were typical of class C beta-lactamases. The enzymes were identified as CMY-2, CMY-4 and a new CMY-variant beta-lactamase, CMY-12. The AmpC beta-lactamases from the two K. pneumoniae isolates were found to be encoded on self-transferable plasmids. The genes encoding the AmpC-type beta-lactamase produced by the three P. mirabilis isolates were chromosomal. Four of the five clinical isolates were from patients transferred from Greece, Algeria and Egypt; one of the K. pneumoniae strains was recovered from a French patient. PFGE analysis and rep-PCR fingerprinting showed that the two P. mirabilis isolates from Greek patients were closely related.

Cross Infection↗
PubMed2002

Beta-lactamases of Kluyvera ascorbata, probable progenitors of some plasmid-encoded CTX-M types.

Kluyvera ascorbata produces a beta-lactamase that results in an atypical susceptibility pattern, including low-level resistance to penicillins, cephalothin, and cefuroxime, but this resistance is reversed by clavulanate. Ten nucleotide sequences of the corresponding gene, bla(KLUA), were obtained and were found to have minor variations (96 to 100%). Otherwise, bla(KLUA) was found to be similar (95 to 100%) to some plasmid-encoded CTX-M-type beta-lactamases. Finally, mobilization of bla(KLUA) on a plasmid was found to be mediated probably by a genetic mobile element like ISEcp1.

Enterobacteriaceae↗